| Popis: |
Arabidopsis TBP-ASSOCIATED FACTOR15b (TAF15b) is a plant-specific component of the transcription factor IID (TFIID) complex. TAF15b is involved in the autonomous pathway for flowering and represses transcription of FLOWERING LOCUS C (FLC), a strong floral repressor in Arabidopsis. Although the components of the autonomous pathway for flowering have been studied extensively, little is known about the functional partners of TAF15b and the mechanism of how TAF15b works. Here, we show that C-TERMINAL DOMAIN PHOSPHATASE-LIKE 1 (CPL1) is a physical and functional partner of TAF15b for the transcriptional repression of FLC. CPL1 is a protein phosphatase that dephosphorylates C-terminal domain (CTD) of RNA polymerase II (Pol II). Through the immunoprecipitation and mass spectrometry technique, we fished out the CPL1 protein as an interacting partner of TAF15b. Similar to taf15b, the cpl1 mutant showed a late-flowering phenotype caused by the increase of FLC expression. In addition, FLC increase in cpl1 was correlated with the enrichment of phosphorylated Pol II in FLC chromatin as expected. We also found that CPL1 and TAF15b share additional common target genes through transcriptome analysis. Such results suggest that the TAF15b–CPL1 complex directly represses transcription through dephosphorylation of Pol II, especially at the FLC locus. |
